Preparation of hyperbranched polyarylenes

ABSTRACT

Highly branched, functionalized, wholly aromatic poly(arylenes) are prepared by the polymerization of AB n  -type aromatic monomers.

This is a division of U.S. patent application Ser. No. 07/341,072, filedApr. 20, 1989 now U.S. Pat. No. 5,070,183 which is a division of U.S.patent application Ser. No. 07/129,151 filed Dec. 7, 1987, now U.S. Pat.No. 4,857,630.

BACKGROUND OF THE INVENTION Field of the Invention

This invention relates to hyperbranched, functional poly(arylenes) andtheir preparation.

References

P. J. Flory J. Amer. Chem. Soc., 74, 2718 (1952); "Principles of PolymerChemistry", Cornell University Press, 1953, pp 361-370, discusses thetheory of condensation polymerization of so-called AB_(n) -type monomerswherein A and B functions condense together to form branched highpolymers which attain high molecular weight without gelation. The theorypredicts that polymerization of such monomers containing one A and nBfunctions leads to randomly branched polymers containing one unreacted Afunction and (n-1)x+1 unreacted B functions where x is the number ofmonomer units, said polymers being more polydisperse the higher thedegree of polymerization. Examples of monomers of this type given byFlory are benzyl halides XCH₂ --C₆ H₅, alkali metal salts oftrihalophenols and D-glucose; the polymers are said to be soluble,non-crystalline and fusible when correctly prepared. Fully aromaticmonomers of the AB_(n) type, or polymers therefrom, are not disclosed.

Denkewalter et al. U.S. Pat. No. 4,289,872 disclose highly branchedpolyamides composed of at least four successive layers of lysine units,prepared by polycondensation of selected amino or carbonyl functions.Baker et al. U.S. Pat. No. 3,669,939 disclose highly branchedcondensation polymers prepared from polyhydroxymonocarboxylic acids(OH)_(n) R--CO₂ H wherein R is a hydrocarbon radical of up to 22 carbonatoms optionally interrupted by a heteroatom, and n is 2-6. Monomersdisclosed as particularly suitable are those of the formula (HOCH₂)₂--C(R³)CO₂ H where R³ is alkyl or --CH₂ OH. Aromatic monomers are notexemplified and apparently not contemplated.

Tomalia et al. U.S. Pat. Nos. 4,587,329, 4,568,737, 4,588,120, 4,507,466and WO 84/02705 disclose dense star polymers containing core, corebranches and terminal groups. These polymers are built up, layer afterlayer, from a core substance by selective condensation of functionalgroups; each successive layer becomes a core for the subsequent layer.Only aliphatic polyamides and polyethers are exemplified. The monomersare of the AB_(n) type and the polymers therefrom are said to be solubleand to have a molecular volume less than 80% of that of a conventionalextended star polymer made from similar materials, molecular diametersbeing less than 2000 angstrom units.

M. Maciejewski J. Macromol. Sci.-Chem., A17 (4), 689 (1982) describeshis concept of so-called shell topological compounds, preparation ofwhich includes polymerization of a monomer of the XRY_(n) type, where nis at least 2. Such polymerization results in a "cascade branched(uncrosslinked) molecule of spherical structure". Equations are providedwhich correlate, among other properties, molecular weight with spherediameter. Although monomers employed in the present invention are of theXRY_(n) type, the reference does not suggest polymerization of arylenemonomers or the physical properties of the polyarylenes therefrom.

Several aryl-aryl coupling reactions are known. Miyaura et al. Synth.Comm, 11(17), 513 (1981) disclose the Pd-catalyzed coupling reaction ofphenyl boronic acid with aryl halides, including aryl bromides, to givethe corresponding biaryls: C₆ H₅ --B(OH)₂ +Br--C₆ H₄ --Z→C₆ H₅ --C₆ H₄--Z where Z is an inert substituent. Arylboronic acids are said to havemajor advantages over other organometallic compounds for couplingreactions of this type, and are said to be available in wide varietythrough use of functionalizing reactions of the parent arylboronic acid,such as nitration, oxidation and halogenation. This reference alsodiscloses Pd or Ni-catalyzed coupling between aryl halides and arylmagnesium or zinc compounds. Preparation of dihaloarylboronic acids fromtrihaloarylenes via mono lithium intermediates is known or obvious;lithium dibromobenzene preparation is disclosed by Chen et al., J.Organomet. Chem., 251, 149 (1983).

Thompson et al. J. Org. Chem., 49(26), 5237 (1984) disclose the couplingof arylboronic acids with 5-bromonicotinates to yield 5-arylnicotinates.

Yamamoto et al., Bull. Chem. Soc. Japan, 51, 2091 (1987) disclosecoupling of aryl halides such as p-chloro and p-bromobenzene and1,3,5-trichlorobenzene in the presence of magnesium and a compound of atransition metal such as Ni or Pd to give polymers. These monomers areof the A₂ or A₃ type wherein only like functions are involved. Thisreference also discloses non-polymerizing coupling of aromatic Grignardreagents RMgX and aryl halides R'X, catalyzed by a transition metal, togive the product R--R'; R and R' can be aryl.

J. Lindley, Tetrahedron, 40(9), 1433 (1984) discloses coupling of arylhalides with aryl copper compounds to form diaryl compounds. I. P.Beletskaya, J. Organomet. Chem., 250, 551 (1983) discloses aryl-arylcoupling of aryl halides with aryltrialkyltin compounds.

None of the prior art discloses highly branched, functionalized, whollyaromatic poly(arylenes) prepared by the polymerization of ABn-typearomatic monomers, nor suggest the properties exhibited by suchpolymers.

SUMMARY OF THE INVENTION

The present invention provides:

(1) A soluble hyperbranched polyarylene having (i) at least one branchper 10 monomer units; (ii) (n-1)x+1 functional groups selected from Br,I or Cl wherein n is the number of halogen atoms in the monomer and isat least 2, and x is the number of monomer units; and (iii) a sphericaldiameter of less than 1000 angstrom units (10⁻⁴ mm), preferably lessthan 100 angstrom units (10⁻⁵ mm);

(2) the polyarylene of (1) wherein the functional groups have beenreplaced by polar or non-polar substituents;

(3) the polyarylene of (2) wherein the substituents are essentiallylinear polymer radicals, each containing at least 3 repeat units, thusforming a star polymer;

(4) a blend comprising up to 50 mol % of the polyarylene of (1);

(5) a blend comprising up to 50 mol % of the polyarylene of (2);

(6) a process for preparing the polyarylene of (1) comprisingpolymerizing the arylene of the formula Ar(X)_(n) M wherein:

Ar is an (n+1) valent arylene radical containing at least one aromaticring, said ring(s) optionally containing one or more substituents thatare inert under polynmerizing conditions;

X is Br, Cl or I; and

M is selected from --B(OH)2, --MgX, --Cu, --Li and --SnR₃ where R is ahydrocarbyl group of 1 to 10 carbon atoms, and X and n are defined asabove, in the presence of a catalyst which is an organopalladium (0) ororganonickel (II) compound when M is --B(OH)₂, --MgX or --SnR₃, and anoxidizing agent such as a ferric or manganic salt when M is Li. Nocatalyst is required when M is --Cu.

DETAILS OF THE INVENTION

Arylene monomers useful in the invention process include those whereinAr is monocyclic or polycyclic; the latter may be a fused ring system ora ring assembly or a combination thereof. Any of the monomers mayoptionally contain one or more substituents that are inert underpolymerizing conditions. Preferably, Ar contains 1-4 unfused aryl ringswith the n+1 valences extending symmetrically from outer ringextremities; preferably this Ar group is trivalent. Examples ofpreferred trivalent Ar radicals include 1,3,5- benzenetriyl,3,5,4'-biphenyltriyl, 1,3,5-benzenetriyl-4',4"-bis(phenyl-) and1,3,5-benzenetriyl-4,4',4"-tris(phenyl-). Preferred inert substituentsinclude alkyl and alkoxyl having 1-4 carbon atoms.

Preferably X is Br or Cl and M is --B(OH)₂.

The arylene monomers used herein are either known compounds or can beprepared by known methods. The Grignard monomers wherein M is --MgX canbe prepared by reacting a polyhalide containing at least three halogensubstituents with one equivalent of Mg.

Monomers wherein M is --B(OH)₂ are prepared from the monolithiumintermediate by treatment with trialkyl borate solution in a suitablesolvent such as diethylether or tetrahydrofuran at a low temperaturebelow about -20° C., preferably below about -50° C., followed by acidichydrolysis.

Monomers wherein M is --M¹ R₃ can be prepared from the lithiumpolyhalide intermediates, which are in turn prepared frompolyhaloarylenes by reaction with a lithium alkyl as described by Chenet al., J. Organomet. Chem., 251, 149 (1983). Monomers wherein M is --Cumay also prepared from metallated (e.g. lithiated) polyhaloarylenes byreaction with a copper halide.

In the process of the invention, an arylene Ar(X)_(n) M is polymerizedin a suitable solvent in the presence of a catalyst at a temperature ofabout 0° to about 150° C., preferably about 20° to about 100° C.Polymerization is conveniently carried out at the solvent's refluxtemperature. Pressure is not critical, but atmospheric pressure ispreferred. Suitable solvents include non-polar liquids such as toluene,xylene and 1-methyl naphthalene, and polar liquids such astetrachloroethane, diphenyl ether, dimethylformamide andtetrahydroguran. The catalyst employed depends on the identity of M inthe monomer, as described above. When M is --B(OH)₂ or a derivativethereof, it is desirable to add a base such as sodium- or potassiumcarbonate, as demonstrated in the Examples.

Polymerization of arylene monomers of the formula Ar(X)_(n) M occurs by1:1 coupling of X and M groups, and leads inevitably to a highlybranched structure because X groups outnumber M groups by at least 2:1.Although the M functions listed above are known to be operable in thepresent invention process, it is believed that any chemoselectivearyl-aryl coupling of polyhaloarylenes can lead to the desiredhyperbranched polymers.

The polymers of the invention have number average molecular weight (Mn)in the range of about 1,000 to about 1,000,000, preferably about 2,000to about 60,000. Molecular weight and polydispersity have been found todepend on the solvent used for the polymerization, as shown in Example1C.

The hyperbranched polyarylenes of the invention are essentiallyamorphous with very high glass transition temperatures (Tg). Forexample, the polymers prepared as described in Example 1 have Tg's ofabout 240° C. Moreover, the polymers are very stable, showing littletendency to decompose in air by thermogravimetric analysis (TGA) belowabout 550° C.; at 350°, for example, a weight loss of 4.5% was observedafter 60 h with a polyarylene prepared in Example 1.

The hyperbranched polyarylenes are at least 10% branched, i.e. theycontain at least one branch per 10 monomer units. Preferably thepolymers are at least 25% branched. It is to be understood that theas-polymerized polyarylenes are wholly aromatic, containing no aliphaticgroups or linkages. During polymerization only single bonds betweenarylene groups are formed. Essentially all of the residual X groups atthe end of polymerization are believed to be located at the outersurfaces of the globular polyarylene molecules.

The polymers of the invention are also very soluble in certain organicliquids, including 1-methylnaphthalene, diphenyl ether, tetrahydrofuran(THF), tetrachlorethane (TCE) and o-dichlorobenzene. They are somewhatsoluble in toluene, xylene and benzene. Because of their halogenfunctionality, the hyperbranched polymers can be reacted further viathese functions with halogen-active reagents. One convenient method isto replace halogen with lithium by reaction with a lithium alkyl such asn-butyl lithium. The lithiated polymers then readily undergo anionicreactions at low temperatures (e.g. -78° ) with a variety ofelectrophilic compounds to provide hyperbranched polymers having otherdesirable functions. Suitable electrophilic compounds includetrialkylchlorosilanes, DMF, alkyl sulfates, ketones, alkylchloroformates, aldehydes, and carbon dioxide.

Alternatively, the original halogen groups in the polymer can be reactedwith Grignard compounds, preferably in the presence of a catalyst such aNi (II) compound; e.g. a bromo functional polymer of the invention canbe reacted with p-methoxyphenyl magnesium bromide, resulting in thereplacement of bromo groups with p-anisole groups. In most instances,these derivatives are also soluble.

The derivatized polymers can be further modified by known chemicalreactions, as will be apparent to those skilled in the art. For example,methoxyl groups in p-anisole derivatives of the invention polymers canbe converted to hydroxy groups by reaction with BBr₃ in methylenechloride. Carboxyl groups can be reduced, e.g. by borane reduction, tohydroxymethyl groups which can, in turn, be converted to chloro- orbromomethyl groups by reaction with the appropriate halogenating agent.Alkali metal or ammonium salts of carboxy-functional hyperbranchedpolymers are soluble in water. Hydroxy and carboxy-functionalpolyarylenes have reduced solubility in non-polar solvents such aso-dichlorobenzene or TCE; however, the addition of a small amount ofalcohol markedly increases solubility in such solvents.

The following ia a non-limiting list of functional groups that have beenintroduced into polyarylenes of the invention by replacement of halogento provide soluble derivatives: --H, --SiR₃ (R is C₁₋₃₀ alkyl), --R¹(alkyl, aryl, alkaryl or aralkyl optionally substituted with alkyl,hydroxy or halogen groups), --C.tbd.CR, --CH═CHR (R is H or alkyl oraryl or alkaryl or aralkyl or combinations thereof), --CH(OH)CH₃, --CHO,--CO₂ R, --CO₂ M' (M' is H, alkali metal or ammonium), --CH₂ OH,--C(CH₃)₂ OH, --CH₂ X, --COX (X is halogen), --CH₂ OR, --CH₂ N(SiR₃)₂,--CN, --Si(OR)₃, --CH₂ NHCHO, --NR, --CONR₂, --B(OR')₂ where R' is H orC₁₋₄ alkyl. The preferred functional groups are --H, --CH₃, --Si(CH₃)₃,--C.tbd.CH, --CH₂ OH, --CO₂ H, --COCl, --CO₂ Li and ##STR1##

The hyperbranched polyarylenes may also be modified by grafting otherpolymers at a halogen-containing or derivatized site to form graftcopolymers. For example, polymers having vinylic, acetylenic or arylhalide end groups can be linked to the present polymers; or polymershaving electrophilic end groups can be linked to lithium-substitutedpolyarylenes.

The hyperbranched polyarylenes can also initiate polymerization fromfunctionalized sites. For example, a polyarylene containing1,1-dimethlcarbinol sites obtained by reacting the polyarylene lithium,prepared as described above, with acetone, can initiate cationicpolymerization of many monomers such as butadiene, isoprene or styrenein the presence of Lewis acid catalysts. Alternatively, anionicpolymerization of similar monomers can be initiated from lithiated sitesor from magnesium chloromethyl sites; the latter are prepared byreacting chloromethyl sites in the hyperbranched polyarylene withfreshly prepared magnesium.

Polymerization of monomers from functional sites in the presentpolyarylenes, or grafting of other polymers to such sites, leads to starcopolymers, the number of arms of which is determined by the number ofactive sites in the "core" polyarylene. Such star copolymers frequentlyexhibit two Tg's reflecting the core and arm polymers. However, if thearms are long, i.e. having a degree of polymerization (DP) of at least50, only a single Tg close to that of the linear homopolymer may beobserved.

Anions from carboalkoxy or hydroxy-functional hyperbranched polyarylenescan also initiate ring-opening of cyclic monomers such as lactones,lactams, lactides or epoxides.

Star polymers prepared from hyperbranched polyarylenes of the inventionare also soluble and are widely useful as dispersing agents or rheologycontrol agents in paint or coating formulations. The initialpolyarylenes, or derivatives thereof, including star polymers, may alsobe blended with other polymers so as to tailor desired properties. Thelarge number of functional groups possible with the polyarylenes permitsblending with a wide variety of other polymers. The presence of a highconcentration of halogen in the initial polyarylenes render themexcellent fire retarding agents for use in blends with other materials.

The addition of a polyarylene of the invention, preferably ahalogen-functional polyarylene, to one or more different polymers, e.g.polystyrene or poly(methyl methacrylate), significantly increases thephysical strength of the latter, at the same time reducing its meltviscosity (see Example 5B). It has also been found that the thermalstability of other polymers can be markedly increased by blending withminor amounts of a halogen-functional polyarylene.

The hyperbranched polyarylenes and derivatives thereof are spherical inconformation. The diameters of the polyarylenes can be calculated fromthe molecular weight and degree of polymerization using Maciejewski'sequation modified for the appropriate aryl-aryl and aromatic C--C bonddistances. Spherical conformation is known to result in unusually lowviscosity in solution or the molten state for polymers of a givenmolecular weight. For this reason the present polyarylenes areespecially useful as viscosity control agents in bulk or solutionformulations with other polymers, as indicated above, and/or with otherformulating ingredients.

In the following embodiments of the invention, parts and percentages areby weight and temperatures are in degrees Celsius unless otherwisespecified. Molecular weights (weight Mw and number Mn average) weredetermined by gel permeation chromatography (GPC); polydispersity, D, isgiven by the ratio Mw/Mn. Degree of branching was determined by carbonnuclear magnetic resonance (CNMR). Thermogravimetric analysis (TGA) wasused to determine polymer stability.

EXAMPLE 1 A. Preparation of 3,5-Dibromobenzene Boronic Acid

To 9.44 g of 1,3,5-tribromobenzene in 200 mL of diethyl ether was added19.4 mL of 1.55M n-butyllithium in hexane at -78° under nitrogen. Thesuspension was stirred for 30 min, then added to 30 mL of trimethylborate in 300 mL of diethyl ether at the same temperature. The now clearsolution was stirred at -78° for 30 min then warmed to room temperatureovernight. Fifty mL of 1 N hydrochloric acid were added and allowed toreact for 2 h. The aqueous layer was discarded and the ether layer wasextracted with 2 N sodium hydroxide solution (5 times with 100 mL). Theextract was washed once with 50 mL of ether, then acidified with 6N HClto pH 2 at 0°. A white precipitate was collected by filtration after thesolution had been kept at 0° for 2 h. After air drying, 8.49 g (95%) ofthe title product was obtained. Melting point was >300° and the puritywas confirmed by chromatography.

B. Polymerization of 3,5-Dibromobenzene Boronic Acid

To a mixture of 50 mL of xylene, 20 mL of 1M aqueous sodium carbonatesolution and 30.8 mg of palladium tetrakis(triphenylphosphine) was added2.98 g of the product of Part A dissolved in 5 mL of ethyl ether. Thereaction mixture was refluxed for 11 hours (internal temperature 88°),then cooled to room temperature. Polymer product precipitated duringcooling and was collected by filtration, washed with 100 mL of water andthen 200 mL of methanol. After drying at reduced pressure, 1.03 g ofpowdered polyarylene was obtained. A further 100 mg was obtained fromthe filtrate by evaporation to dryness followed by a water and methanolwash. GPC resulted in Mn 5000 and Tg 237.6°.

C. Polymerization of 3,5-Dibromobenzene Boronic Acid

The experiment of Part B was repeated except that 100 mL of xylene and20 mL of 1M aqueous potassium carbonate solution were used, the reactionmixture was refluxed for 6 h, and the product was precipitated by adding100 mL of petroleum ether. The polymer was recovered and washed withmethanol and water. After vacuum drying, 0.86 g of polymer was obtained.

The above polymerization was successfully repeated 4 times using1-methylnaphthalene, diphenyl ether, tetrachloroethane anddimethylformamide, respectively, in place of xylene as the solvent. Theresults are summarized in the Table and show a marked effect of solventon the molecular weight and polydispersity of the hyperbranchedpolyarylene products.

    ______________________________________                                        SOLVENT        -- Mn      -- Mw   D                                           ______________________________________                                        Xylene         3,820      5,750   1.50                                        Ne Naphthalene 6,560      13,300  2.02                                        Phenyl Ether   5,280      8,560   1.62                                        Tetrachlorethane                                                                             4,070      5,230   1.28                                        Dimethylformamide                                                                            2,000      2,750   1.38                                        ______________________________________                                    

EXAMPLE 2 Preparation and Polymerization of 3,5-DichlorobenzeneMagnesium Chloride ##STR2##

A mixture of 5 g of potassium and sodium alloy (56:44) and 8.89 g ofanhydrous magnesium chloride in 200 ml tetrahydrofuran (THF) was stirredat room temperature for one hour before refluxing for two hours. Aftercooling to room temperature, 13.64 g of 1,3,5-trichlorobenzene in 50 mlof THF was added over 1.5 hours during which time the reactiontemperature was maintained below 35° C. The solution was then stirredfor 10 hours at room temperature after which 105 mg ofbis(triphenylphosphine)nickel dichloride was added, and the resultingreaction mixture refluxed for 24 hours. Most of the THF was removedunder reduced pressure and the polymer product precipitated by methanoladdition. After two precipitations 5.60 g of polymer was obtained:Tg=236° C.; Mn=7560; MW=17500; D=2.30.

EXAMPLE 3 Derivatization of Bromo-Functional Polyarylene (I) ##STR3##

To 5.56 g of the polymer I, prepared by the polymerization of3,5-dibromobenzene boronic acid as in Example 1B, in 250 mL of THF wasadded 28 mL of 1.55M n-butyl lithium in hexane, keeping the temperaturebelow -70° C. After about 10 ml of butyl lithium was added, aprecipitate of lithiated polyarylene (II) appeared. Meanwhile, carbondioxide gas was vigorously bubbled through 250 mL of THF in a 1 L roundbottom flask for 15 min, then the solution of II was cannulated into it.CO₂ gas addition was continued for a further 20 min and the precipitatedII gradually redissolved. The solution was warmed to room temperatureand THF was removed under reduced pressure. Diethyl ether was added toprecipitate the lithium salt of the carboxylated polymer; yield 5.56 gafter drying. The salt was dissolved in water and acidified with 3N HCl;the polymer III precipitated out and was collected by filtration.

EXAMPLE 4 Reduction of --CO₂ H functions in a Polyarylene ##STR4##

To 2.5 g of polymer III, prepared as in Example 3 and dissolved in 150mL of THF, was added, at room temperature under argon and via a syringe,10 mL of 10M borane methyl sulfide complex. The mixture was refluxedovernight. Excess borane was destroyed with sodium bicarbonate solution,and THF was removed under reduced pressure. The hydroxymethyl derivativeIV precipitated and was suspended in water, neutralized with 3N HCl,then collected by filtration and air-dried. 1.95 g of product wasobtained.

A second sample of polyarylene IV, prepared as above, was purified asfollows: the impure polymer was Soxhlet-extracted with 10% THF inmethanol. The solvent was concentrated to about 20 mL, and 20 mL ofmethylene chloride and 100 mL of petroleum ether were added. The whitepolymer thus obtained was filtered and dried under vacuum. The reactionwas confirmed by the disappearance of the IR carbonyl peak at 1700 cm⁻¹.NMR analysis showed about 70% overall conversion of the bromo-functionalpolyarylene I to the hydroxymethyl derivative IV.

EXAMPLE 5 Conversion of Hydroxymethyl Functions to ChloromethylFunctions in a Polyarylene

To 200 mL of THF was added 10.5 g of triphenyl phosphine and 6.0 g ofN-chlorosuccinimide at 0°. After warming to room temperature for 30 min,3.72 g of the polymer IV from Example 4 was added as a powder. Themixture was stirred for 24 h at room temperature and 5 mL of ethanol wasadded to destroy residual phosphonium complex. THF was removed underreduced pressure, and the precipitated polymer was dissolved in 20 mL ofmethylene chloride. The white chloromethyl-functional polyarylene (V)was reprecipitated by adding 150 mL of methanol, filtered and driedunder vacuum. Yield 2.57 g. The polyarylene structure was confirmed byelemental NMR and IR analysis.

Numerous other derivatives were prepared from polyarylene I either bydirect replacement of halogen or by preparing the lithiated derivativeII as in Example 3 or by preparing the bromomagnesium (Grignard)derivative and reacting either derivative with various electrophilicreagents to introduce the functions listed on page 9. A Ni (II) catalystis desirable in reactions of polymeric Grignard reagents.

EXAMPLE 6 Preparation of a Polyarylene-Poly(methyl methacrylate) StarPolymer ##STR5## where X is Cl⁻ or Br⁻.

To 206 mg of MgBr₂ etherate, 17 mg of lithium and 178 mg of anthracenewas added 50 mL of THF under argon. The mixture was stirred overnight.Then 124.6 mg of polymer V prepared as in Example 5 was added as apowder at room temperature. 5.0 mL of methyl methacrylate (MMA) wereadded via a syringe. An exothermic reaction occurred. The reaction wasquenched by addition of ethanol, THF was removed at reduced pressure,and the polymer was precipitated by addition of ethanol. 5.0 g ofpolymer was obtained. The degree of polymerization (DP) of the PMMA armswas expected from theory to be 65. DP values of 36 and 43 weredetermined, respectively, by ¹³ C NMR and CPC. NMR and IR spectra of thePMMA arms indicate a syndiotactic structure; and a single Tg of 127.3°was observed.

A similar star polyarylene-PMMA polymer having a DP of about 8, showedspectra similar to the above star polymer, but two Tg's, at 106.6° and232.6° were observed.

Two polyarylene-polystyrene star polymers, prepared by substitutingstyrene for MMA in the above procedure, were found to have DP's (arms)of about 50 and about 7; each exhibited only one Tg, at 105.6° and143.7° respectively.

EXAMPLE 7 Preparation of a Polyarylene-polystyrene Blend

To 2.0 g of bromo-functional polyarylene I, prepared as in Example 1B,in 500 mL of distilled THF, were added 38.0 g of commercial polystyrenehaving an Mn of about 260,000. THF was removed slowly at reducedpressure to half its original volume, and the remaining slurry wastransferred to an aluminum pan. Solvent was removed completely and thepolymeric blend containing 5% of polyarylene I was cut into small piecesand dried under high vacuum for 2 days.

A 0.1% blend of polyarylene I, prepared as above, in polystyrene wasprepared in a similar manner as a control. The melt viscosity of the 5%blend, determined by capillary rheometry, was about 50% of that of thecontrol at 180° and about 80% of the control at 120°. The decrease inmelt viscosity in the presence of the polyarylene is greater at highershear rates.

In an independent experiment, the molecular weight of the controldecreased to 24% of its original value when exposed to air at 220° for 4h with some shear force applied. Under the same conditions the molecularweight of the 5% blend decreased to 65% of its original value.

EXAMPLE 8 Preparation of Polyarylene ##STR6## R=H R=CH₃

R=Si(CH₃)₃

To 200 ml of a THF solution containing 6.20 g of polymer I was added28.8 ml of 1.6N n-butyllithium in hexane at -78° C. during 15 minutesfollowed by stirring for 30 minutes at the same temperature. To thecooled reaction mixture was added 10 ml of methanol in 100 ml THF. Thecooling bath was then removed and the solution warmed to roomtemperature. THF was partially removed under reduced pressure and thepolymer product precipitated by methanol addition. After drying avanilla colored powder was obtained. Elemental analysis indicated that71% of the bromine had been replaced by hydrogen. Similarly preparedpolymer, which was quenched with acetonitrile, then methanol, exhibiteda Tg=127° C. Methylation and trimethylsilylation were done under similarconditions with dimethyl sulfate and trimethylsilyl chloriderespectively.

    ______________________________________                                                                Conversion Tg                                         R        Reagent        (%) method (°C.)                               ______________________________________                                        H        Acetonitrile              127                                        H        Methanol       81 (anal.)                                            CH.sub.3 Dimethyl Sulfate                                                                             74 (NMR)   179                                        TMS      Trimethylsilyl 87 (NMR)   152                                                 Chloride                                                             ______________________________________                                    

EXAMPLE 9 Preparation of an Acetylenic Polyarylene ##STR7##

To 15.50 g of polymer I in 500 ml of THF was added 10.7 ml of2-methyl-3-butyn-2-ol, 1.83 g triphenylphosphine, 244 mg cupric acetate,108 mg PdCl₂ and 41.8 mg triethylamine. The solution was degassedquickly twice followed by refluxing for 48 hours. After cooling to roomtemperature, the reaction mixture was filtered and the precipitate waswashed with THF. The filtrate was concentrated to 50 ml and polymer VIwas precipitated by methanol addition. Proton NMR indicated 32%substitution by the 2-methyl-3-butyn-2-ol group. To a solution ofpolymer VI in 150 ml of dry THF was added 4.0 g of dry powderedpotassium hydroxide. The reaction mixture was refluxed for one hourafter which acetone was removed by azeotropic distillation. When thesolvent volume was reduced to 20 ml, the mixture was cooled, and another150 ml of THF added. Azeotropic distillation was repeated twice. Afterthis treatment, the polymer was dissolved in 20 ml of THF, insolublesremoved by filtration, and the solution poured into 100 ml of methanol.The resulting precipitate was collected by filtration and dried undervacuum at room temperature to yield 3.57 g of polymer VII. The infraredspectrum of the product exhibited two peaks characteristic of acetylenicgroups at 3300 and 2100 cm⁻¹.

EXAMPLE 10 Preparation of a Bromomethyl Polyarylene ##STR8##

To 15.50 g of the polymer I, prepared by the polymerization of3,5-dibromobenzene boronic acid as in Example 1B, in 500 ml of THF wasadded 70 ml of 1.6N n-butyllithium in hexane at -78° C. The additiontook about an hour, after which the reaction mixture was stirred for anadditional 30 minutes at -78° C. To this slurry was added 10.0 ml ofbromomethyl methyl ether in 50 ml of THF. The mixture was slowly warmedto room temperature, after which 50 ml of conc. NH₄ OH solution wasadded. Polymer VIII was precipitated by methanol addition. NMR analysisindicated 68% substitution of the methoxymethyl group, while elementalanalysis indicated 75% replacement. To 5.0 g of polymer VIII in 200 mlof methylene chloride was added 5 ml of boron tribromide at -78° C.,stirred for one hour at that temperature, and then warmed to roomtemperature during one hour. After about an additional 30 minutes atroom temperature, the solution was cooled to 0° C., and 10 ml of asodium bicarbonate solution added. Methylene chloride was evaporated and200 ml of methanol added. Polymer IX was filtered, suspended in 200 mlwater for 30 minutes, refiltered, and washed with methanol. Polymer IXwas dried under high vacuum overnight. Elemental analysis indicated 50%substitution of bromomethyl groups.

EXAMPLE 11 Preparation of an Amido Polyarylene ##STR9##

The oil was removed from 4.8 g of a 50% sodium hydride/oil dispersion bywashing twice with 20 ml of toluene. To this was added 200 ml ofdimethyl acetamide, which had been dried overnight over 5A molecularsieves, and 4.50 g formamide. The reaction mixture was stirred for 45minutes, 1.00 g polymer IX added, and then heated at 60 C. for 5 hours;during this time a light yellow fine precipitate settled to the bottomof the flask. After cooling to room temperature, about 10 ml of methanolwas added, and the solution poured into 300 ml of chilled water. A whiteflocculant precipitate was collected by filtration and dried overnight.The polymer was dissolved in 100 dimethyl acetamide and insolublesseparated by filtration. The filtrate was poured into 100 ml water, theprecipitated polymer collected by filtration, and then dried to obtain0.41 g of product which displayed peaks characteristic of amide groupsat 1635 cm⁻¹ and 1675 cm⁻¹ in the infrared spectrum. Reaction withacetamide afforded acetyl aminomethyl ended polymer which displayed anamide peak in the infrared spectrum at 1630 cm⁻¹.

EXAMPLE 12 Preparation of an Acid Chloride Functional Polyarylene##STR10##

To 360 mg of polymer III, with carboxylic end groups, in 5 ml THF, wasadded 395 mg pyridine and 590 mg thionyl chloride at room temperatureunder a nitrogen atmosphere. The reaction mixture was stirred for threedays, insolubles separated by filtration, followed by evaporating thesolvent to dryness. An orange colored material, 300 mg, which displayedan infrared carbonyl peak of 1770 cm⁻¹ was obtained.

I claim:
 1. A process for preparing soluble hyperbranched polyarylenescomprising dissolving in a solvent an arylene monomer of the formulaAr(X)_(n) M wherein:Ar is an (n+1) valent arylene radical containing atleast one aromatic ring: X is Br, Cl or I; M is --B(OH)₂, --MgX or--SnR₃ where R is a hydrocarbyl group containing 1 to 10 carbon atoms;and n is the number of halogen atoms in the monomer;adding a catalystwhich is an organopalladium(0) compound or an organonickel(II) compound;refluxing the mixture at the solvent reflux temperature for a timesufficient to convert the monomer to polyarylene, and isolating thepolyarylene.
 2. A process for preparing soluble hyperbranchedpolyarylenes comprising dissolving in a solvent an arylene monomer ofthe formula Ar(X)_(n) M wherein:Ar is an (n+1) valent arylene radicalcontaining at least one aromatic ring: X is Br, Cl or I; M is --Li; andn is the number of halogen atoms in the monomer;adding a catalyst whichis a ferric salt or a manganic salt; refluxing the mixture at thesolvent reflux temperature for a time sufficient to convert the monomerto polyarylene, and isolating the polyarylene.
 3. A process forpreparing soluble hyperbranched polyarylenes comprising dissolving in asolvent an arylene monomer of the formula Ar(X)_(n) M wherein:Ar is an(n+1) valent arylene radical containing at least one aromatic ring: X isBr, Cl or I; M is --Cu; and n is the number of halogen atoms in themonomer; refluxing the mixture at the solvent reflux temperature for atime sufficient to convert the monomer to polyarylene, and isolating thepolyarylene.
 4. A process as in claim 2 or 3 wherein the arylene monomerof the formula Ar(X)_(n) M contains 1-4 unfused aryl rings in which Aris trivalent.
 5. A process as in claim 4 wherein the trivalent radicalsare selected from the group consisting of 1,3,5-benzenetriyl3,5,4'-biphenyltriyl, 1,3,5-benzenetriyl-4',4"-bis(phenyl-) and1,3,5-benezenetriyl-4,4',4"-tris(phenyl-).
 6. A process as in claim 4wherein said monomer contains at least one inert substituent selectedfrom the group consisting of alkyl and alkoxyl, having 1-4 carbon atoms.7. A process as in claim 1 wherein:X is Br or Cl; and M is --B(OH)₂. 8.A process as in claim 1 wherein M is --B(OH)₂ and said M results from aboronic acid prepared from monolithium intermediates.
 9. A process as inclaim 1, 2 or 3 wherein the polymerization is conducted at atmosphericpressure and a temperature of about 20 to about 100° C.